Multi-camera systems allow for simultaneous capture of content from different viewpoints. In environments in which multiple cameras or capture devices are operating simultaneously, image stills or video clips recorded at the same may be combined (for instance by a post-processing system) to produce an immersive image/video experience. Globally unique media identifiers (GUMIs) uniquely identify individual image or video content and may be used to associate simultaneously-captured images/video. However, a post-processing system must physically access the media storage of each individual capture device in order to reconcile simultaneous captures. Synchronization information must be stored in such a way as to remain associated with content files independent of the storage medium used to store the content files.